[TYPO3-mvc] How to use an own DateTime class?

[Stephan Reuther - development.IT]

Hi,

I just wrote an own DateTime class (Tx_MyExt_Util_DateTime extends DateTime).
Is there a configuration option to tell Extbase for using my own class
instead of the raw DateTime Object?

Due to my tca->dbtableName->dateProperty->eval = 'datetime' configuration
extbase detects the value to be interpreted as DateTime and directly  
instanciates
a new DateTime from the value (in  
DataMap.php->convertFieldValueToPropertyValue)

Furthermore extbase does not call my setter  
$myObject->setDateProperty(), where
I could recast the DateTime to Tx_MyExt_Util_DateTime.

So my question is:
Am i doing something wrong with my configuration and it should work  
with the correct
one, or are such configuration options not yet implemented.

Greetings,
stephan